1. Field of the Invention
The present invention relates to a particle-removing apparatus for a semiconductor device manufacturing apparatus and to a method of removing particles, and more specifically it relates to a particle-removing apparatus that prevents the falling of particles that are generated during a process onto a wafer, and to a method for removing particles.
2. Description of the Related Art
Particles that are generated in the process of manufacturing a semiconductor device, and in particular in a process that makes use of plasma, are a cause of reduced yield and a deterioration of uptime. These particles can be caused by the peeling off of substances that have been deposited within the process equipment by reactions and by growth of substances generated by reaction within the plasma. To prevent the falling of these particles onto a substrate, as described in the Japanese Unexamined Patent Publications (KOKAI) No. 5-29272 and No. 7-58033, there has been a proposal of an apparatus in which the substrate is covered after a process is completed.
FIG. 9(a) is a drawing that shows a plasma etching apparatus of the past, in which the reference numeral 2100 denotes a processing chamber, inside which are provided an upper processing electrode 2200 and a lower processing electrode 2300, the upper processing electrode 2200 being grounded, and a high-frequency power supply 2400 being connected to the lower processing electrode 2300.
Above the lower processing electrode 2300 there is provided an electrostatic chuck electrode 2700, which is insulated by means of an insulator 1900, a voltage being applied to this electrostatic chuck electrode 2700 from a power supply 2600, so as to hold a semiconductor substrate 3000. The processing chamber 2100 is provided with an intake port 3100 for processing gas and an exhaust port 3200. A cover 3600 is provided so that particles do not fall onto the semiconductor substrate 3000.
FIG. 9(b) illustrates the general equipment operation cycle of a plasma etching process in a semiconductor device manufacturing process.
This process is for the case of a cycle in which a single substrate is processed. The substrate 3000, which is transported from a transporting port 3800, is transported to within the processing chamber 2100, at which point the process gas is introduced from the process gas intake port 3100. When the pressure within the processing chamber 2100 reaches a prescribed value, a high-frequency voltage is applied from the power supply 2400, so as to generated a plasma that etches the substrate 3000. Simultaneously with the above, the substrate 3000 is held by the electrostatic chuck. After completion of the etching, the supply of the high-frequency voltage, the supply of the process gas, and the electrostatic chuck are all stopped. After several seconds, an inert gas that does not contribute to etching is supplied for a prescribed amount of time in order to quickly purge the chamber of the process gas. The substrate 3000, after completion of this processing, is transported to outside the processing chamber 2100 from the transporting port 3800.
In an apparatus of the past as described above, in order to prevent particles from falling onto the substrate 3000, the cover 3600 is provided over the substrate 3000. According to an experiment by the inventor, however, in a semiconductor device manufacturing process that uses plasma, the timing of the falling of particles onto a substrate was shown to be intimately connected with the operating status of the semiconductor device manufacturing apparatus. Specifically, in the above-noted publications of the past, there was absolutely no consideration given to the timing of the covering of the substrate, this representing a major problem with regard to not being able to prevent the attachment of particles to the substrate.
Accordingly, it is an object of the present invention to improve over the above-noted drawback in the prior art, in particular by providing a novel particle-removing apparatus of a semiconductor device manufacturing apparatus and a method of removing particles whereby, by controlling the timing of the covering by a cover provided over the substrate in accordance with the processing condition of the substrate, the attachment of particles that are generated within the manufacturing apparatus during a process that uses plasma to the substrate is prevented.
It is another object of the present invention to provide novel particle-removing apparatus of a semiconductor device particle and method of removing particles whereby, by making use of the characteristic that particles are positively charged, attachment of the particles to the substrate is prevented without the use of a cover or the like.